The bronchial veins are small vessels that return blood from the larger bronchi and structures at the roots of the lungs. The right side drains into the azygos vein, while the left side drains into the left superior intercostal vein or the accessory hemiazygos vein. The bronchial veins are counterparts to the bronchial arteries. The veins, however, do not return all of the blood supplied by the arteries; much of the blood that is carried in the bronchial arteries is returned to the heart via the pulmonary veins. [WP,unvetted]. [ http://en.wikipedia.org/wiki/Bronchial_veins ]